1. Field of the Invention
The present invention relates to a production line for producing a display panel such as a liquid crystal panel and in particular, to a display panel production line including a cutting step area for cutting a glass substrate into a size of display panel, an injection step area for filling the display panel with liquid crystal, and a sealing step area for sealing the liquid crystal injection opening, wherein the panel filled with the liquid crystal is carried in a cassette between the areas.
2. Description of the Related Art
Generally, display panels are used as output display units of electronic apparatuses. Among the display panels, liquid crystal panels are widely used for display of personal computers and word processors because of low power consumption, thin and small weight, and low voltage drive.
As shown in a perspective view and a front view of FIG. 9, two glass substrates, i.e., a TFT substrate 1 and a color filter substrate 2 are bonded together via a seal 3, leaving a gap of 5 to 6 micrometers. This gap is filled with liquid crystal. It should be noted that a liquid crystal injection opening 4 is provided at the lower end of the liquid crystal panel where no seal 3 is provided
In general, such a liquid crystal panel is produced by the steps shown in FIG. 10. Firstly, a large-area glass substrate is subjected to washing, drying, orientation film printing, rubbing, seal printing, and the like, which will be referred to as a TFT substrate formation step 5. Thus, a TFT substrate 1 is produced. On the other hand, another large-area glass substrate is subjected to washing, drying, orientation film printing, rubbing, spacer distribution, and the like, which will be referred to as a color filter substrate formation step 6. Thus, a color filter substrate 2 is produced.
Next, the color filter substrate 2 is superposed on the TFT substrate 1 with a gap, which will be referred to as a superposing step 7. Thus two glass substrates are bonded to each other.
The large-area glass substrates are cut into a plurality of liquid crystal panels with a size corresponding to type 12 to type 15, which will be referred to as a cutting step 8. The cutting is performed by using a diamond cutter to scribe the surface of the TFT substrate 1 and the color filter substrate 2, after which a shock is applied so as to separate the liquid crystal panels along the scribe. A liquid panel which has been cut out has a configuration as shown in FIG. 9.
After the cutting step 8 complete, liquid crystal injection step 9 is performed to fill the liquid crystal panel gap with a liquid crystal material. This liquid crystal injection step 9 is performed as follows. Firstly, as shown in FIG. 11, a liquid crystal vessel 11 containing a liquid crystal material 10 and a plurality of liquid panels P is placed in a vacuum chamber 12 and the air is discharged from the vacuum chamber 12. Next, when the pressure in the vacuum chamber 12 has become sufficiently low, the liquid crystal injection opening 4 of the liquid crystal panel is immersed in the liquid crystal material 10, and then atmospheric air is introduced into the vacuum chamber 12 so as to be under atmospheric pressure. Thus, the gap is filled with the liquid crystal material 10 by the capillary phenomenon and by the pressure difference between the pressure inside the liquid crystal panel and the pressure of the vacuum chamber 12.
After injection of the liquid crystal material 10 is complete in the liquid crystal injection step 9, the liquid crystal injection opening 4 is sealed in the sealing step 13, thus sealing the liquid crystal material 10. The sealing step 13 includes wiping off, UV resin application, and UV radiation. After this, a polishing step, a polarizing plate attachment step, an inspection step are performed to complete the liquid crystal panel.
It should be noted that in the production line performing the aforementioned steps, a cassette is used for storing and carrying the liquid crystal panel after the cutting step 8. In general cassettes used have an identical outer configuration, so as to be able to contain various sizes of the liquid crystal panel. If the cassettes have different outer configurations, the automation line may be disturbed. Moreover, in order to carry panels of different sizes, a holding plate as a partition is moved to hold the panel in the cassette.
However, the conventional liquid crystal panel production steps have problems as follows.
These years, for the variety of application fields, a larger liquid crystal panel is required. Moreover, for assuring a wide angle of visibility and for increasing the display speed response, a smaller gap is required. In order to realize a large panel with a smaller gap, the time required for liquid crystal injection per a unit number of panels has greatly increased in comparison to the other steps. For example, the liquid crystal injection step 9 requires 4 or 5 times more than the cutting step 8 and the sealing step 13. Accordingly, in the liquid crystal panel production line, it is necessary to improve the time efficiency of the liquid crystal injection step 9.
Here, it can be considered to increase the number of liquid crystal injection apparatuses which are expensive in general or to use a cassette of larger outer configuration to store more panels. However, this may affect the other existing steps and the production line, and not preferable from the viewpoint of costs. Actually, it is necessary to improve the production efficiency of the entire production line.
It is therefore an object of the present invention provide a display panel production line capable of improving the production line so that a variety of liquid crystal panels including a large-area panel with a reduced gas can be produced in a single production line, even in an automated line using a normalized cassette for the respective steps.
The display panel production line according to the present invention (Claim 1) comprises: a cutting step area for cutting a glass substrate into a display panel size; an injection step area for injecting liquid crystal into the display panel; and a sealing step area for sealing a liquid crystal injection opening of the display panel which has been filled with the liquid crystal; wherein a predetermined cassette is used as a medium to contain and convey the display panel between the areas, the display panel production line further comprising a relocation area for converting the number of display panels contained in the cassette.
With this configuration, it is possible to process more liquid panels as a processing unit number in the liquid crystal injection step than in the cutting step and the sealing step. Moreover, this configuration can be used without modifying a cassette currently used in the cutting step and the sealing step.
As a result, when it is necessary to increase the processing unit number of the liquid crystal panels in the liquid crystal injection step, considering the variety of the liquid crystal panel types and improvement of the entire production line, the processing unit number can be increased in the relocation step area and when there is not such a need, the production line can be used without the relocation step area.
Accordingly, even when using a conventional production line as it is, there is no need of increasing the number of the liquid crystal injection apparatuses and it is possible to improve the liquid panel production step and the entire production line efficiency without affecting any other existing steps and the production line.
According to another aspect of the invention (Claim 2), the relocation step area includes a display panel relocation apparatus for relocating panels from a cassette exhausted from the cutting step area, into a cassette to be supplied to the injection step area. In this relocation, more panels are placed in the cassette to be supplied to the injection step than in the cassette exhausted from the cutting step area.
With this configuration, it is possible to process more liquid panels as a processing unit number in the liquid crystal injection step than in the cutting step and the sealing step. Moreover, this configuration can be used without modifying a cassette currently used in the cutting step and the sealing step.
As a result, when it is necessary to increase the processing unit number of the liquid crystal panels in the liquid crystal injection step, considering the variety of the liquid crystal panel types and improvement of the entire production line, the processing unit number can be increased in the relocation step area and when there is not such a need, the production line can be used without the relocation step area.
Accordingly, even when using a conventional production line as it is, there is no need of increasing the number of the liquid crystal injection apparatuses and it is possible to improve the liquid panel production step and the entire production line efficiency without affecting any other existing steps and the production line.
According to still another aspect of the invention (Claim 3), the relocation step area includes a display panel relocation apparatus for relocating panels from a cassette exhausted from the injection step area, into a cassette to be supplied to the sealing step area. In this relocation, less panels are placed in the cassette to be supplied to the sealing step than in the cassette exhausted from the injection step area.
With this configuration, it is possible to process more liquid panels as a processing unit number in the liquid crystal injection step than in the cutting step and the sealing step. Moreover, this configuration can be used without modifying a cassette currently used in the cutting step and the sealing step.
As a result, when it is necessary to increase the processing unit number of the liquid crystal panels in the liquid crystal injection step, considering the variety of the liquid crystal panel types and improvement of the entire production line, the processing unit number can be increased in the relocation step area and when there is not such a need, the production line can be used without the relocation step area.
Accordingly, even when using a conventional production line as it is, there is no need of increasing the number of the liquid crystal injection apparatuses and it is possible to improve the liquid panel production step and the entire production line efficiency without affecting any other existing steps and the production line.
According to yet still another aspect of the present invention (Claim 4), the relocation step area includes a first display panel relocation apparatus for relocating display panels from a cassette exhausted from the cutting step area, into a cassette to be supplied to the injection area while increasing the number of panels relocated; and a second display panel relocation apparatus for relocating display panels from a cassette is exhausted from the injection step area, into a cassette to be supplied to the sealing step area while decreasing the number of display panels relocated.
With this configuration, it is possible to process more liquid panels as a processing unit number in the liquid crystal injection step than in the cutting step and the sealing step. Moreover, this configuration can be used without modifying a cassette currently used in the cutting step and the sealing step.
As a result, when it is necessary to increase the processing unit number of the liquid crystal panels in the liquid crystal injection step, considering the variety of the liquid crystal panel types and improvement of the entire production line, the processing unit number can be increased in the relocation step area and when there is not such a need, the production line can be used without the relocation step area.
Accordingly, even when using a conventional production line as it is, there is no need of increasing the number of the liquid crystal injection apparatuses and it is possible to improve the liquid panel production step and the entire production line efficiency without affecting any other existing steps and the production line.
According to still another aspect of the present invention (Claim 5), the relocation step area includes a display panel relocation apparatus which relocates display panels from the cassette exhausted from the cutting step area, into a cassette to be supplied to the injection step area, while increasing the number of display panels relocated, and which relocates the display panels from the cassette exhausted from the injection area, into a cassette to be supplied to the sealing step area, while decreasing the number of display panels relocated.
With this configuration, it is possible to process more liquid panels as a processing unit number in the liquid crystal injection step than in the cutting step and the sealing step. Moreover, this configuration can be used without modifying a cassette currently used in the cutting step and the sealing step.
As a result, when it is necessary to increase the processing unit number of the liquid crystal panels in the liquid crystal injection step, considering the variety of the liquid crystal panel types and improvement of the entire production line, the processing unit number can be increased in the relocation step area and when there is not such a need, the production line can be used without the relocation step area.
Accordingly, even when using a conventional production line as it is, there is no need of increasing the number of the liquid crystal injection apparatuses and it is possible to improve the liquid panel production step and the entire production line efficiency without affecting any other existing steps and the production line.
According to yet another aspect of the present invention (Claim 6), there is provided a display panel production line as claimed in Claim 2 to Claim 5, wherein the display panel relocation apparatus comprises: a filled cassette supply mechanism for supplying a cassette containing the display panels in the longitudinal direction; an empty cassette exhaust mechanism for exhausting an empty cassette from which the display panels have been removed; an empty cassette supply mechanism for supplying a cassette to which the display panels are to be relocated; a filled cassette exhaust mechanism for exhausting the cassette to which the display panels have been relocated; and a display panel relocation unit for taking out display panels at a take-out station located at a transfer position between the filled cassette supply mechanism and the empty cassette exhaust mechanism and storing the display panels at a storage station located at a transfer position between the empty cassette supply mechanism and the filled cassette exhaust mechanism.
With this configuration, it is possible to automatically change the number of display panels relocated in a single cassette. That is, when a cassette containing liquid crystal panels are conveyed from the cutting step to the liquid crystal injection step, the liquid crystal panels are removed from the first cassette exhausted from the cutting step and then placed in the second cassette to be supplied to the liquid crystal injection while increasing the number of panels in the second cassette compared to the first cassette. Moreover, when the cassette is conveyed from the liquid crystal injection step to the sealing step, the panels are removed from the second cassette and relocated into a third cassette to be supplied to the sealing step while decreasing the number of panels in the third cassette. Moreover, the cassette which has become empty is automatically ejected and an empty cassette to contain liquid crystal panels is automatically supplied. Thus, relocation of liquid crystal panels can be performed with a high efficiency.
Accordingly, it is possible to increase the number of liquid crystal panels to be processed at once in the liquid crystal injection step without changing the number of liquid crystal panels processed in the other steps.
According to yet another aspect of the present invention (Claim 7), the display panel relocation unit is arranged almost at the center of the display panel relocation apparatus, so as to be sandwiched by a cassette supply entrance of the filled cassette supply mechanism and a cassette exit of the filled cassette to exhaust mechanism on one side and a cassette exit of the empty cassette exhaust mechanism and a cassette supply entrance of the empty cassette supply mechanism on the other side.
With this configuration, one side of the apparatus can be used for supply and eject of a cassette containing display panels and the other side can be used for supply and eject of an empty cassette.
Accordingly, when applying the display panel relocation apparatus to a production line, it is possible to separate an area handling a cassette containing display panels and an area handling an empty cassette. This enables to improve the efficiency of the production line.
According to yet another aspect of the present invention (Claim 8), the take-out station and the storage station have a cassette feed mechanism for modifying the position for taking out the display panels from the cassette and the position for storing the display panels into the cassette.
With this configuration, when taking out or storing display panels from/into a cassette, it is possible to shift to cassette position, so that only a predetermined number of display panels can be taken out or stored.
According to still another aspect of the present invention (Claim 9), the display panel relocation apparatus includes a cassette rotation mechanism provided in the cassette supply mechanism and the cassette exhaust mechanism.
With this configuration, when taking out display panes or storing display panels from/into a cassette, it is possible to change a cassette direction in a horizontal plane.
This increases the degree of freedom concerning the display panel take-out direction and storage direction with respect to the cassette.
According to yet another aspect of the present invention (Claim 10), the cassettes have identical external dimensions.
By using such cassettes, it is possible to improve the efficiency of the production procedure and production line without suppressing automation of the display panel production line.
According to yet still another aspect of the present invention (Claim 11), the cassette is constituted by a pair of outer frames, a plurality of slide shafts bridged between the outer frames, and a pair of display panel holding plates for holding the display panels, and at least one of the display panel holding plates can slide on the slide shaft and can be fixed at an arbitrary position.
By using such cassettes, it is possible to store display panels of various sizes. Accordingly, even when producing display panels of different sizes, it is possible to maintain automation of the display panel production line and to increase the efficiency of the production procedure and the production line.
According to yet another aspect of the present invention (Claim 12), the display panel relocation unit includes: a display panel vertical movement mechanism which can move between a location below the take-out station and a location between the storage station and support the bottoms of the display panels so as to take out upward the display panels from the cassette or store downward the display panels; a display panel holding mechanism for holding the bottoms and sides of the display panel taken out of the cassette; and a lateral feed mechanism which can move from a location above the take-out station to a location above the storage station.
With this configuration, it is possible to hold the top, bottom, and both sides of the display panels when relocating the display panels all at once. This enables to relocate the display panels without causing scars or scratches on the display panel surfaces.
According to yet still another aspect of the present invention (Claim 13), the display panel vertical movement mechanism includes a display panel support roller which can move along the bottom of the display panels.
With this configuration, it is possible to move the display panels up and down without touching the liquid crystal injection opening provided at the bottom of each display panel.
Accordingly, it is possible to prevent attachment of dusts to the liquid crystal injection opening.
According to still another aspect of the present invention (Claim 14), a wiper mechanism for removing stains from the display panel support roller is provided below the take-out station and below the storage station.
With this configuration, stains attached to the display panel roller can be removed only by a small displacement of the displacement panel vertical mechanism which moves between the locations below the take-out station and the location below the storage station and the display panel support roller moving along the bottoms the display panels.
Thus, it is possible to prevent attachment of dusts the liquid crystal injection opening.
According to yet another aspect of the present invention (claim 15), the display panel top support mechanism includes a display panel top pitch correction mechanism having two-plated comb-shaped member in which one plate can be slightly shifted with respect to the other plate.
With this configuration, when supporting the display panels, it is possible to correct the display panel top pitch and accordingly, it is possible to align the display panels when taking out the display panels from a cassette and storing the display panels into another cassette,
According to yet another aspect of the present invention (Claim 16), the display panel holding mechanism includes a bottom receiving roller for supporting the bottom of the display panels and a side receiving roller for supporting the sides of the display panels.
With this configuration, after the display panels are lifted by the display panel vertical movement mechanism, it is possible to simultaneously support the display panel bottoms and side surfaces. Accordingly, after the display panels are lifted by the display panel vertical movement mechanism, the support roller can easily be removed.
According to still another aspect of the present invention (Claim 17), the wiper mechanism for removing stains from the bottom receiving roller is arranged at both ends of the lateral movement stroke orbit of the lateral feed mechanism.
With this configuration, stains attached to the bottom receiving roller can easily be removed only by a small displacement of the lateral feed mechanism and the display panel holding mechanism.
Accordingly, it is possible to prevent attachment of dusts to the liquid crystal injection opening.
According to still another aspect of the present invention (Claim 18), the display panel relocation unit includes a display panel side pitch correction mechanism having two-plated comb-shaped member in which one plate can be slightly shifted with respect to the other plate.
With this configuration, when supporting the display panels, a simple mechanism can correct the display panel side pitch and align the display panels when storing them into a cassette.
According to yet another aspect of the present invention (Claim 19), the display panel relocation unit is arranged with an inclination of small angle in the pitch direction of the display panels.
With this configuration, the display panels are all inclined by the gravity and the display panels are arranged with an identical pitch.
According to yet still another aspect of the present invention (Claim 20), the display panel production line further comprises a cassette positioning mechanism for correcting a stop position of the cassette at the take-out station and the storage station.
With this configuration, it is possible in jog mode to accurately determine the position of the cassette from which display panels are taken out or into which display panels are stored. This prevents breakage of the display panels when taking out or storing display panels from/into a cassette.